Situated on the coast of the East China Sea, Zhenhai has been known from ancient times as "Hai Tian Xiong Zhen"--"grand town facing the sea" and "Zhe Dong Men Hu"--"gateway of east Zhejiang Province". It is here the Yongjiang River, which receives the Yuyao River and Fenghua River at Sanjiangkou in the downtown of Ningbo City, flows eastward into the sea. Right at the mouth of the Yongjiang River on its north and south banks stand Zhaobao Hill and Golden Rooster Hill, which are like a gate that guards the town against the water of the East China Sea. Thus it has its name "Zhenhaikou". For its position, Zhenhaikou has been an important strategic point for coast defense.

Zhenhaikou used to be a battlefield where today remain numerous coast defense works which witnessed the heroic and soul-stirring struggles of the Chinese army and the people from the southeast coastal areas in their resistance of the pirates and invaders from Japan, England and France. It is here in the Ming Dynasty (1368-1644), many famous generals, such as Lu Tong, Yu Dayou, Qi Jiguang, led their armies to fight fierce battles against Japanese invaders and made brilliant military victories. During the First Opium War (1840-1842), Lin Zexu, a national hero, came to Zhenhai to supervise the building of the defense work and cannons, war chariots and boats, which crowned him with eternal glory. Yu Qian, the Imperial Commissioner and Governor-general of Jiangsu and Zhejiang, led his army to fight fiercely against British invaders and died heroically. During the Sino-French War (1884-1885), the soldiers and people of Zhenhai, led by generals Liu Bingzhang, Ouyang Lijian, Xue Fucheng, Yang Qizhen, Du Guanying and Wu Jie, defeated the French fleet--the only complete victory that the Chinese people made in coastal battles in the history of Chinese anti-aggression wars in modern times. During the War of Resistance against Japan, the soldiers and the people of Zhenhai, together with guerrillas, defeated the Japanese invasions many times and on July 17, 1940 alone, they killed and wounded more than 400 Japanese invaders.

The sites of coast defense works are scattered on both banks of the Yongjiang River and they form 4 groups of scenes around Ziyin Hill, Jinzi Hill, Zhaobao Hill and Golden Rooster Hill. These sites include military headquarters, looking-out towers, defense walls, campsites, forts, pillboxes, trenches and sentry boxes for alarming, etc. All these relics are well preserved. In order to carry forward the national spirit and help people keep firmly in mind the lesson taught by history that a backward country is bullied by others, the government of Zhenhai District made a decision in 1994 to protect and develop the sites and carry out a project for patriotism education. This decision was enthusiastically echoed by people of various circles and overseas Chinese and they donated more than 10 million yuan for the project. The Central Committee of the Communist Youth League named the sites "National Socialist Education Base for the Youth".